I know that the red and white are Gov't issue and we frequently see them peeping over a piper's spats, but for civilian wear, don't they remind you a little too much of the tablecloth in an Italian restaurant?
I suppose it varies with the individual's personal experience, but that's not the image it conjures up in my mind. I think of formal wear. The white dicing, to my eye, isn't really an "every day" color for hose. Much like the so-called dress tartans, the addition of white seems to lend itself toward formality. I really like the more civilian look of red/black, blue/black, green/black, or other non-white color combinations in diced hose.

Now that we have established that they need no special flashes of their own, does anyone care to offer a theory on which colors look best in which situations? Do you go for tone matching or high contrast, or do you try to pickup one color? Or do you give up on matching and just wear 'em? Personally, I think I understand the idea of not matching pretty well, but I also understand that you probably didn't just find a pair of $120 hose in your sock drawer without some thought or intention. So, how does we choose?
Trying to keep in mind the idea that "matching" doesn't necessarily have to be the main intent, I personally think what's most pleasing to the eye is "coordinating" the colors. You're absolutely right that if one is going to spend a lot of money on diced/patterned hose, one should presumably be dressing with intent. Not just throwing on colors that are ill-suited to each other, or that cause a visual break or distortion in the overall handsome look of a kilt.

I too love Matt's example of subdued colors in the garters that look like they belong with the hose. Especially when wearing castellated hose where the garters are totally exposed. But when wearing turn-down top hose where all you see is the ends of the garters, there's more leeway for the color to act as an accent. And here I think it's best suited to picking up colors in the kilt, especially if they're not present in the 2 colors of the diced hose. It helps coordinate the colors and create a transition effect between the kilt and the hose. But only within the limits of good taste!

When I finally fork out the loot for hand knitted, patterned hose, I'll probably go for something that can compliment any of my tartans. A little bit of yellow, a touch of red, possibly with a green or blue background.
You know, I never gave much thought to how much patterned hose can totally transform the look of a kilt until I (recently) spent the money and got a pair to match my tartan. It really takes the kilted outfit from a somewhat generic look to (dare I say it) sartorial excellence!

You just can't go wrong with patterned hose custom-made to match your tartan. It totally eliminates the fuss over which color hose to choose, and makes garter choice easy too. You'll notice that I'm not wearing garter ties in this picture, but I think it's obvious that I could have chosen red, blue, green, black, or even charcoal and it would work fine. Though, as you noted, traditional portraits often showed patterned hose being worn without visible garters. Maybe in those days they considered it 'over the top'?